The invention relates to a multi-cylinder internal combustion engine including a main combustion chamber located adjacent to the piston and a precombustion chamber connected with the main combustion chamber by a channel. The precombustion chamber includes ignition means as well as an inlet valve for admitting a fuel-air mixture. Another inlet valve admits the appropriate fuel-air mixture to the main combustion chamber.
It is known that an easily ignitable fuel-air mixture must contain ten to fifteen percent fuel and such a mixture then also delivers the highest engine performance. Mixtures which are substantially leaner than that and which would, in principle, be desirable because of the substantially lower concentration of toxic exhaust gases, are ignitable only with greater difficulty. It is for this reason that internal combustion engines having precombustion chambers, so-called stratified-charge engines, have been developed. The precombustion chamber is filled with a relatively rich fuel-air mixture which is then ignited and generates an ignition flame which propagages to the main combustion chamber and leads to the ignition of the somewhat leaner and more difficult to ignite mixture in the main combustion chamber. As a result, the concentration of noxious components in the exhaust is substantially reduced while, at the same time, obtaining a more favorable fuel usage. In the known systems, the fuel is supplied either into the induction tubes associated with the combustion chambers or else directly into the combustion chambers. When direct injection into the combustion chamber is used, considerable injection pressure is required which, in turn, necessitates substantial expense. Furthermore, difficult problems arise regarding the preparation of the fuel-air mixture for direct injection systems. Similar remarks apply to a process in which the main combustion chamber is supplied with a fuel-air mixture through the main engine inlet valve, while fuel is directly injected into the precombustion chamber.
Also known are internal combustion engines of the type generally described above in which the fuel metering for each cylinder is performed in a particular location and a portion of the complete metered-out fuel quantity is then branched off and injected into the precombustion chamber by a separate pump. While this system can dispense with a second fuel metering device for each cylinder which would work synchronously with the first fuel metering device, nevertheless a separate pressurized supply mechanism is required.